Tip: Build Security Tools via Vibe Coding — scan-for-secrets Created with README-Driven Development and Red/Green TDD in Claude Code

Simon Willison·medium signal

Simon Willison documented building scan-for-secrets entirely through Claude Code using README-driven development: write the README first describing desired behavior, then use red/green TDD to implement. The tool detects credentials across multiple encoding schemes (literal, backslash-escaped, JSON-escaped) — a requirement that emerged naturally through the TDD cycle. This approach validates that security-sensitive tooling can be reliably built through agentic coding when the specification is written first and tests gate every implementation step.